We previously demonstrated that tumor-infiltrating lymphocytes (TIL) in human breast cancer sometimes form organized tertiary lymphoid structures (TLS) characterized by CXCL13-producing T follicular helper (Tfh) cells. The present study found that CD4⁺ Tfh TIL, CD8⁺ TIL, and TIL-B, colocalizing in TLS, all express the CXCL13 receptor CXCR5. An ex vivo functional assay determined that only activated, functional Th1-oriented Tfh TIL (PD-1^hiICOS^int phenotype) provide help for immunoglobulin and IFN-γ production. A functional Tfh TIL presence signals an active TLS, characterized by humoral (immunoglobulins, Ki-67⁺ TIL-B in active germinal centers) and cytotoxic (GZMB⁺CD8⁺ and GZMB⁺CD68⁺ TIL plus Th1 gene expression) immune responses. Analysis of active versus inactive TLS in untreated patients revealed that the former are associated with positive clinical outcomes. TLS also contain functional T follicular regulatory (Tfr) TIL, which are characterized by a CD25⁺CXCR5⁺GARP⁺FOXP3⁺ phenotype and a demethylated FOXP3 gene. Functional Tfr inhibited functional Tfh activities via a glycoprotein A repetitions predominant (GARP)-associated TGF-β–dependent mechanism. The activity of tumor-associated TLS was dictated by the relative balance between functional Tfh TIL and functional Tfr TIL. These data provide mechanistic insight into TLS processes orchestrated by functional Th1-oriented Tfh TIL, including TIL-B and CD8⁺ TIL activation and immunological memory generation. Tfh TIL, regulated by functional Tfr TIL, are an expected key target of PD-1/PD-L1 blockade.

中文翻译：

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浸润人乳腺癌的功能性 Th1 导向 T 滤泡辅助细胞促进有效的适应性免疫

我们之前已经证明，人类乳腺癌中的肿瘤浸润淋巴细胞 (TIL) 有时会形成有组织的三级淋巴结构 (TLS)，其特征是产生 CXCL13 的 T 滤泡辅助 (Tfh) 细胞。本研究发现，共定位于 TLS中的 CD4 ⁺ Tfh TIL、CD8 ⁺ TIL 和 TIL-B 均表达 CXCL13 受体 CXCR5。一项离体功能测定确定，只有激活的、功能性 Th1 导向的 Tfh TIL（PD-1 ^hi ICOS ^int表型）才能帮助产生免疫球蛋白和 IFN-γ。功能性 Tfh TIL 的存在标志着活性 TLS，其特征是体液（免疫球蛋白、活性生发中心的Ki-67 ⁺ TIL-B）和细胞毒性（GZMB ⁺ CD8 ⁺和 GZMB ⁺ CD68 ⁺ TIL 加上 Th1 基因表达）免疫反应。对未治疗患者的活动性与非活动性 TLS 的分析表明，前者与积极的临床结果相关。TLS 还包含功能性 T 滤泡调节 (Tfr) TIL，其特征在于 CD25 ⁺ CXCR5 ⁺ GARP ⁺ FOXP3 ⁺表型和去甲基化的FOXP3基因。功能性 Tfr 通过糖蛋白 A 重复占主导地位 (GARP) 相关的 TGF-β 依赖性机制抑制功能性 Tfh 活性。肿瘤相关 TLS 的活性取决于功能性 Tfh TIL 和功能性 Tfr TIL 之间的相对平衡。这些数据提供了对功能性 Th1 导向 Tfh TIL 协调的 TLS 过程的机制洞察，包括 TIL-B 和 CD8 ⁺ TIL 激活和免疫记忆生成。Tfh TIL 受功能性 Tfr TIL 调节，是 PD-1/PD-L1 阻断的预期关键目标。